Why eating 60% of your carbs at lunch is good for fat loss

If you're trying to lose fat, you've probably packed a Mason jar salad with a side of celery sticks and cottage cheese for your midday meal more than once. But according to new research, your low-calorie lunch might actually be working against you.

The science

For the study, researchers recruited 80 overweight and obese women between the ages of 18 and 45, and had them eat their biggest meal of the day (50 percent of their daily calories) at either dinner or lunch for 12 weeks. So their diet and portion sizes broke down like this: 15 per cent of their calories at breakfast, 15 per cent as a snack, 50 per cent at lunch (or dinner), and 20 per cent at dinner (or lunch).

The science translated

What does that translate to, exactly? Though each participant's diet was based on her specific calorie needs, a woman eating 1,500-calorie per day would consume 225 calories at breakfast, another 225 as a snack, 750 calories at lunch, and 300 calories at dinner (or vice versa). That's a big lunch.

In addition to divvying up their calories in a specific way, the women ate a diet that was high in carbs and low in saturated fat. More specifically, 17 percent of their calories came from protein, 23 percent from fat, 60 percent from carbs, and 400 grams (which is a little less than a pound) came from fruits and veggies for fibre.

They were also asked to do 60 minutes of “moderate activity” (like brisk walking) five days a week.

Compared to the group who ate 50 percent of their calories at dinner, the lunch crew had a higher average fat loss—about 13 pounds vs. 9.5 pounds—and a greater reduction in BMI.

The takeaway

So why is a huge lunch better for fat loss than a huge dinner? The study authors suggest that the real reason the lunch group dropped more pounds is because their fasting insulin levels were lower compared to those who ate a majority of their calories at night. As a result, the lunch group kept their blood sugar spikes in check—meaning, they didn't feel super hungry again shortly after eating.

The conclusion

While the fat loss is impressive, it’s worth pointing out that study participants were overweight or obese to begin with. If you aren’t, it’s unlikely you would lose as much fat in such a short period of time on this eating plan.

However, the study raises a good point: Making lunch your big meal of the day, and scaling back on dinner can help keep your fat in check, and may even help you lose some fat.